Improvement in valves for air-brakes



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mmmmmm GHARLES H. PERKINS, OF BLOOMINGTON, ILLINOIS, ASSIGNOR TO GEORGEWES'IINGHOUSE, JR., OF PITTSBURG, PENNSYLVANIA.

IMPROVEMENT IN VALVES FOR PAR-BRAKES.

Specication forming part of Letters Patent No. 63,242, dated May 1l,1875; application filed March 13, 1875.

To all whom t may concern: A

Beit known that I, C. H. PERKINS, of Bloomington, in the county ofMcLean and in the State of Illinois, have invented certain new anduseful Improvements in Valves for Air- Brakes; and do hereby declarethat the following is a full, clear, and exact description thereof,reference being had to the accompanying drawings making a part of thisspecification, in which- Figure 1 is a central longitudinal section ofmy improved apparatus, showing the relative position of parts beforeair-pressure is applied. Fig. 2 is a like view of the same afterpressure is applied, and while the operative parts are in a state ofequilibrium, and Fig. 3 shows the position of said operative parts aftersuch equilibrium has been destroyed and air is passing to thebrake-cylinder.

Letters of like name and kind refer to like parts in each of thefigures.

Thedesign of my invention is nto render more simple and efficient themeans employed for controlling the admission of air to the cylinder ofpneumatic car brakes; to which end it consists, principally, in thecombination of the piston-valve with the cylindrical valvebox, havingits inlet, outlet, and exhaust ports relatively arranged in the mannerand for the purpose substantially as is hereinafter specified.

It consists, further, in combining, with one end of said main valve, aspiral spring, for pressing it toward one end of the valve-box, when nototherwise adjusted, by air-pressure, substantially as and for thepurpose hereinafter set forth.

In the annexed drawings, A represents the l box or casing of my valve,constructed in the form of a hollow cylinder, and having its ends closedby means of removable heads B and B. Upon the upper side of the cylinderA is formed a second supplemental cylinder, C, which corresponds inlength to the same, and has about one-fourth its diameter. One end ofsaid upper cylinder Gis permanently closed, while its opposite end islclosed by means of a removable screw-plug,AD. Small ports E and E areprovided between the ends of the cylinders A and C, an opening', F, isformed at the upper side and longitudinal center of the latter, whilethree openings, G, H, and I, respectively, are provided within the lowerside of said main cylinder A, as shown, the first of said openings Gbeing located near one end, the second opening H at a point j ust beyondthe longitudinal center of said cylinder, While the third opening I islocated at a point about one-third the length of said cylinder from itsopposite end. Within the cylinderA is placed a piston-valve, K, whichhas the form shown 5 is packed with leather 7c at each end 5 and isprovided with a central rod, L, which extends outward from either end,and, by contact with the heads B and B', limits the travel of saidvalve. i A spiral spring, M, placed around one end of said rod L, bearsagainst the head B and the end of said valve, and presses the latter tothe center, longitudinally of said cylinder, as seen in Fig. 2. Upon theinner end of the plug D, which extends inward beyond the port E,vis`formed a seat, d, which, at its center, is provided with an opening, d',that extends longitudinally into said plug, and then radially outwardinto a concentric cavity, d, that is formed by groovin g said plug. Thespace d is directly over the port E, so that air passing from thecylinder A through said port can, by means of said space and the openingd', enter the valve-box G. A valve, N, is fitted within the box G, andallowed such longitudinal motion` therein as t0 enable the opening d tobe uncovered, as seen in Fig. 1; or, by the seating of said valve, to beclosed, as shown by Figs. 2 and 3.

The device is now complete, and being placed beneath a car with theopening G in communication with the air-supply pipe, the opening Fincommunication with the air-tank, and the opening I in communicationwith" the brake-cylinder, operates as follows: The normal position ofparts is, as shown in Fig. l, the main valve K being thrown beyond thecenter of its casing A, so as to connect the ports I and H and permitair to escape from the brake-cylinder, which position remains unchangedas air from the pump is admitted through the opening Ginto said casing,and from the same passes through the port E and passage d into thevalve-box C, from the latter through the opening F into the tanks, andthrough the port E into the opposite end of the main valve-box, thepressure of air upon opposite ends of said valve K being just equal.When it is desired to apply the brake, the pressure Within thesupply-pipe and front end of the valve-box A is decreased, When thepressure Within the opposite end of the latter Will move the valve K tothe position shown in Fig. 3, so as to uncover the outlet-port I andpermit air to pass into the brake-cylinder. When the quantity oi' airpassing into the brake-cylinder has been sufficient to cause thepressure Within the rear end ot' the valvebox A and the tank to nearlyequal the pressure Within the opposite end of said valve-box, the springM Will force the valve K to the central position shown in Fig. 2, andcover the outlet-port I, so as to prevent the escape of air from thebrake-cylinder, and cause the press ure of the brake upon the Wheels tobe maintained. While the brake is on, and the main valve occupies theposition shown in Fig. 2, the pressure Within the tank may be graduallyincreased. If itis desired to apply more power to the brake, thepressure Within the supplypipe is again decreased, when the main valvewill be again forced to the position shown in Fig. 3, and air admittedto the brake-cylinder until the pressure upon opposite ends of saidvalve is equalized as before. To let off the brakes, air-pressure isagain applied to the supply-pipe, and through the same to the front endof the main valve-box A, and, When such pressure equals that Within theopposite end of the latter, the spring M Will force the main valve K inan opposite direction, the port I Will be cut oi from communication Withthe air-tank and placed in communication with the exhaust-port H, whenthe air within the brakecylinder Will escape.

The device described is simple in construction, certain and eftlcient inoperation, and enables the desired Work to be performed by use of asmaller number of parts than are usually employed.

Having thus fully set forth the nature and merits of my invention, whatI claim as new 1s- 1. In combination with the valve-box A, provided Withthe inlet-port Gr, outlet-port I, and exhaust-port H, and connectedthrough suitable mechanism with an air-pressure tank, the valve K,arranged to move longitudinally Within said valve-box, having greaterWidth ot' bearing than, and capable of covering and uncovering', saidoutletport I, and of connecting the same with said exhaust-port H,substantially as and for the purpose speciiied.

2. In combination with the valve-box A and valve K, the spring M, placedbetween one end of said valve-box and said valve, and having such lengthas to cause said valve to cover the outlet-port Whenever theair-pressure upon its ends is equal, substantially as and for thepurpose shown.

In testimony that I claim the foregoing I have hereunto set my hand this8th day of March, 1875.

CHARLES H. PERKINS.

Witnesses:

I. E. EAsrrMAN, FRANK. WHITE.

